Systems and methods for intermedullary bone fixation

ABSTRACT

Systems and methods for intermedullary bone fracture fixation are described herein. The fixation device includes a main body having a flexible state and a rigid state. The fixation device further includes a proximal interface coupled to a proximal end of the main body to anchor the fixation device to an exterior surface of the bone and a distal interface coupled to a distal end of the main body to anchor the fixation device to an interior cavity of the bone. The fixation device further includes a locking interface to configured to convert the main body from the flexible state to the rigid state.

CROSS-REFERENCES TO RELATED PATENT APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 62/063,526, filed Oct. 14, 2014, theentire contents of which are herein incorporated by reference.

This present application relates to U.S. Provisional Application No.61/949,177, titled “Shape Adaptable Intramedullary Fixation Device,”filed on Mar. 6, 2014. This present application further relates to U.S.patent application Ser. No. 14/300,752, titled “Intramedullary FixationSystem for Management of Pelvic and Acetabular Fractures,” filed on Jun.10, 2014, which is a continuation of U.S. patent application Ser. No.14/357,917, which is the U.S. National Stage Entry of InternationalApplication No. PCT/CA2012/050808, filed Nov. 14, 2012, which in turnclaims the benefit of and priority to U.S. Provisional PatentApplication 61/559,609, filed Nov. 14, 2011. The entire contents of theforegoing applications are herein incorporated by reference.

BACKGROUND

The following description is provided to assist the understanding of thereader. None of the information provided or references cited is admittedto be prior art.

The human skeleton has more than two hundred bones that have a range ofshapes and dimensions. When a bone is fractured it may be completelyfractured or partially fractured in any number of ways (crosswise,lengthwise, in multiple pieces). The unique geometry of each bone canmake it difficult to properly fix the bone while it heals.

SUMMARY

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the following drawings and thedetailed description.

Systems and methods for intermedullary bone fixation are describedherein such as shape conforming implantable bone fixation device. In oneaspect, an apparatus for intermedullary bone fixation is provided. Theapparatus includes a main body having a flexible state and a rigidstate. The apparatus further includes a proximal interface coupled to aproximal end of the main body to anchor the fixation device to anexterior surface of the bone and a distal interface coupled to a distalend of the main body to anchor the fixation device to an interior cavityof the bone. The apparatus further includes a locking interfaceconfigured to convert the main body from the flexible state to the rigidstate, wherein the locking interface is coupled to the proximalinterface.

In an embodiment, the main body includes a series of beads, and eachbead in the series of beads includes a central bore and three or morefiber bores positioned around the central bore. The three or more fiberbores may house a three or more fibers that run a length of the mainbody. In an embodiment, the three or more fibers are axially fixed tothe distal interface in the rigid state and the flexible state. Thethree or more fibers are in a fixed position at the proximal interfaceduring the rigid state. In an embodiment, the series of beads of themain body can flex in one or more axis of motion during the flexiblestate.

In some embodiments, each bead includes a pair of lobes positioned atopposing ends of the respective bead and extending perpendicular from afirst surface of the respective bead. Each bead may further include apair of sockets formed into a second surface of the respective bead andpositioned at opposing ends of the respective bead. The pair of socketsis configured to receive the pair of lobes of a preceding bead in theseries of beads to form the series of beads. In an embodiment, each beadincludes a central pivot point on the first surface of the respectivebead that contacts a subsequent bead in the series of beads. The firstsurface of each bead can be configured to limit a bead to beadangulation in the series of beads to a pre-determined angle. Thepre-determined angle may correspond to a minimum bend radius of thefixation device.

In an embodiment, the proximal interface includes an exterior surfacethat connects to the exterior bone surface and an interior surfaceconfigured to receive a driving tool. The proximal interface may includeat least one of a hex, hexalobe, or a star pattern. In some embodiments,the internal surface of the proximal interface includes an access pointto connect the locking interface to a driving tool when the driving toolis inserted into the proximal interface. The proximal interface mayinclude a threaded internal surface to connect with the lockinginterface and a threaded exterior surface to connect with a bonesurface. The threaded exterior surface may have a lower or higher pitchthan the threaded internal surface.

In an embodiment, the locking interface includes a locking screw, athreaded portion, an outer shell housing a pair of fibers, a lockingram, and a locking face. The locking screw can be configured to receivea driving tool via an access point in the proximal interface. In anembodiment, the locking screw is configured to advance the locking ramand the locking ram is configured to rotate each fiber of the pair offibers housed in the outer shell in opposing directions. A distal end ofthe locking ram may include a pair of faces configured to rotate thepair of fibers. The contour of the locking face can be the same as acontour of the pair of faces of the distal end of the locking ram. In anembodiment, the pair of faces of the distal end of the locking ram clampthe pair of fibers to the locking face in the rigid state.

In some embodiments, the locking interface includes a series of plates.Each plate in the series of plates includes a central bore and a pair offiber bores to house a pair of fibers. When the central bore of eachplate is offset relative to the central bore of a subsequent plate inthe series of plates, the fixation device is in the flexible state. Inthe flexible state, the pair of fiber bores of each plate is inlinerelative to the pair of fiber bores of a subsequent plate. In anembodiment, a locking pin inserted through the central bore of eachplate when the fixation device is in the rigid state. In the rigidstate, the central bore of each plate is inline relative to the centralbore of a subsequent plate in the series of plates and the pair of fiberbores of each plate is offset relative to the pair of fiber bores of asubsequent plate.

In an embodiment, the locking interface includes a locking screw, aninterior body comprising an externally tapered shape, and an outer bodyincludes an internally tapered shape. The interior body may include acentral bore to receive a guide wire and a plurality of fiber bores tohouse a plurality of fibers. A distal end of the locking screw mayinclude a cap configured to contact the interior body to advance theinterior body to a tapered portion of the outer body when the lockingscrew is rotated clockwise. In some embodiments, the locking screw isconfigured to retract the interior body when the locking screw isrotated counter clockwise.

In an embodiment, the distal interface includes a threaded outer surfaceto anchor the fixation device to the interior cavity of the bone whenthe fixation device is installed in the interior cavity of the bone anda central bore.

In another aspect, a method for delivering a fixation device to a boneof a patient is provided. The method includes a delivering the fixationdevice in a flexible state into an interior cavity of the bone via anaccess point in the bone. The bone includes a fracture. The methodfurther includes rotating a proximal end of the fixation device using adriving tool to secure a distal end of the fixation device into theinterior cavity of the bone. The proximal end may be rotated until theproximal end is flush with the access point of the bone. The methodfurther includes actuating a locking interface of the fixation devicevia the proximal interface to convert the fixation device from aflexible state to a rigid state.

The method further includes accessing a surface of the bone via acannula inserted into a soft tissue region of the patient andestablishing the access point in a surface of the bone to insert thefixation device into the interior cavity of the bone. A guide can bedelivered to the interior cavity of the bone via the access point and isinserted to a pre-determined point past the fracture in the bone. Adiameter of the interior cavity of the bone can be increased using areamer installed over the guide.

In an embodiment, the fixation device includes a main body including aseries or beads, a proximal interface coupled to a proximal end of themain body; a distal interface coupled to a distal end of the main body;and a locking interface configured to convert the fixation device from aflexible state to a rigid state. Each bead in the series of beads caninclude a central bore and three or more fiber bores positioned aroundthe central bore. Three or more fibers run a length of the main body andeach of the three or more fiber bores houses one of the three or morefibers. In an embodiment, the three or more fibers are axially fixed tothe distal interface in the rigid state and the flexible state.

The method further includes converting the three or more fibers to afixed position at the proximal interface in the rigid state. In someembodiments, each bead includes a pair of lobes positioned at opposingends of the respective bead and extending perpendicular from a firstsurface of the respective bead. Each bead may further include a pair ofsockets formed into a second surface of the respective bead andpositioned at opposing ends of the respective bead. The pair of socketsare configured to receive the pair of lobes of a preceding bead in theseries of beads to form the series of beads. Each bead may include acentral pivot point on the first surface of the respective bead thatcontacts to a subsequent bead in the series of beads.

In an embodiment, the first surface of each bead is configured to limita bead to bead angulation in the series of beads to a pre-determinedangle, the pre-determined angle corresponding to a minimum bend radiusof the fixation device. The method further includes securing theproximal interface to an exterior surface of the bone such that theproximal interface is flush with the access point of the bone. Themethod further includes rotating the proximal interface to engage athreaded exterior surface of the proximal interface with the exteriorsurface of the bone. In some embodiments, the proximal interfaceincludes at least one of a hex, hexalobe, or a star pattern to receive adriving tool. An internal surface of the proximal interface may includean access point to connect the locking interface to the driving toolwhen the driving tool is inserted into the proximal interface. Themethod further includes actuating the locking interface via the interiorsurface of the proximal interface to convert the fixation device from aflexible state to a rigid state. The locking interface can moveindependent of the proximal interface.

In an embodiment, the proximal interface includes a threaded internalsurface and the threaded exterior surface has a higher pitch than thethreaded internal surface. The method further includes receiving, by alocking screw of the locking interface, a driving tool via an accesspoint in the proximal interface and rotating the locking screw toactuate a locking ram of the locking interface. The method furtherincludes advancing the locking ram to rotate each fiber of a pair offibers housed in the locking interface. The pair of fibers may berotated from the flexible state to the rigid state and vice-versa. Adistal end of the locking ram may include pairs of faces configured torotate pairs of fibers. The method further includes clamping of fibers,between the face of the locking interface, and the ram of the lockinginterface in the rigid state.

In an embodiment, the locking interface includes a series of plates andeach plate in the series of plates includes a central bore and a pair offiber bores to house a pair of fibers. In some embodiments, the centralbore of each plate is offset relative to the central bore of asubsequent plate in the series of plates when the fixation device is inthe flexible state and the pair of fiber bores of each plate is inlinerelative to the pair of fiber bores of a subsequent plate when thefixation device is in the flexible state. In some embodiments, theseries of stacked plates includes a locking pin inserted through thecentral bore of each plate when the fixation device is in the rigidstate. The central bore of each plate can be inline relative to thecentral bore of a subsequent plate in the series of plates when thefixation device is in the rigid state and the pair of fiber bores ofeach plate can be offset relative to the pair of fiber bores of asubsequent plate when the fixation device is in the rigid state.

The method further includes actuating an interior body of the lockinginterface with a distal end of a locking screw of the locking interfaceand advancing, by the locking screw, the interior body to a taperedportion of an outer body of the locking interface when the locking screwis rotated clockwise. The method may include retracting, by the lockingscrew, the interior body when the locking screw is rotated counterclockwise. The method further includes anchoring a threaded outersurface of the distal interface to the interior cavity of the bone.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several embodiments in accordance with thedisclosure and are; therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings.

FIG. 1 depicts a fixation device for fixing a bone fracture inaccordance with an illustrative embodiment.

FIGS. 2a-2c depict various views of a proximal interface of a fixationdevice in accordance with an illustrative embodiment.

FIG. 2d depicts an alternative embodiment of a proximal interface inaccordance with an illustrative embodiment.

FIG. 3a depicts a locking interface of the fixation device in accordancewith an illustrative embodiment.

FIG. 3b depicts a locking interface in an unlocked state in accordancewith an illustrative embodiment.

FIG. 3c depicts a locking interface in a locked state in accordance withan illustrative embodiment.

FIGS. 3d and 3e depict a cross sectional locking interface in unlockedand locked states, respectively, in accordance with an illustrativeembodiment.

FIG. 3f depicts an alternative embodiment of a locking interface inaccordance with an illustrative embodiment.

FIG. 4a depicts a main body of a fixation device in accordance with anillustrative embodiment.

FIGS. 4b-4d depict various views of a bead of the main body of thefixation device in accordance with an illustrative embodiment.

FIG. 5a depicts a distal interface of a fixation device in accordancewith an illustrative embodiment.

FIG. 5b depicts an alternative view of a distal interface in accordancewith an illustrative embodiment.

FIG. 6 depicts a flow diagram of a method for delivering a fixationdevice to a bone of a patient and converting the device from a flexibleto rigid sate in accordance with an illustrative embodiment.

FIG. 7a depicts a locking interface in the unlocked position with acollet housing, collet, and collet lock in accordance with anillustrative embodiment.

FIG. 7b depicts a collet and collet lock in accordance with anillustrative embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be used, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presented here.It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, and designed in a widevariety of different configurations, all of which are explicitlycontemplated and make part of this disclosure.

The unique geometry and/or curvature of a bone can make it difficult toproperly fix a bone while it is healing. For example, stable pelvic ringinjuries rarely result in major long-term problems because their initialtreatment is straightforward and their recovery uneventful and complete.However, patients with unstable pelvic ring injuries are morechallenging to treat and may suffer from complications. For example, 25%to 75% of patients with an unstable pelvic fracture will suffer someform of incomplete recovery, according to a number of studies. For casesthat are treated surgically, mal- and non-unions can still occur.Inadequate reduction and fixation can lead to a number of problems,including pain, pelvic tilt, impaired gait, leg-length discrepancy,scoliosis, difficulties in sitting, and restrictions in activities ofdaily life, sexual dysfunction, urinary system complaints, andnon-unions with implant breakage.

Bone fractures in general may occur in both long bones, where internalfixation may be performed using long straight internal fixationmechanisms, or in bones with some complex curvature, where use of astraight internal fixation device becomes limited based on the boneradius of curvature. The minimally invasive internal fixation of archedbone structures, specifically where straight screws cannot provideproper fixation, or access limits the installation of straight screws,or necessitates invasive procedures to apply plates or external fixationdevices.

The present disclosure is directed to an apparatus such as a fixationdevice for a bone fracture in a patient. The fixation device includes anelongated structure with a proximal bone interface, a shape-lockinginterface, a main body, and a distal bone interface. The main body iscapable of converting from a flexible state, via the shape lockinginterface, in which the main body of the device can flex in one or moreaxis, to a rigid state. In the rigid state, the fixation device cansupport the loads required in the healing phase of patient treatment.The fixation device may also revert into the flexible state for thepurpose of device removal. The conversion from one state to anotherprovides the compliance needed to attain access into and thru archedinternal bone passages from a single point, and after conversionmaintains the final arched geometry necessary to maintain the relativeposition of the fractured bone segments. The position of bone fragmentsalong the axis of the fixation device is maintained by the proximal anddistal bone interfaces.

FIG. 1 depicts a fixation device 100 for fixing a bone fracture inaccordance with an illustrative embodiment. The fixation device 100includes a proximal interface 110, a locking interface 120, a main body130, and a distal interface 140. A bone fracture 150 may be present typein the hard exterior surface of a bone 160, such as the cortical bone.In other embodiments, the bone fracture may be present in a cancellousbone region of the bone 160. In some embodiments, the bone fracture 150is present through both the cortical bone and the cancellous bone.

In an embodiment, the term “fix” or “fixing” as used herein may refer toproviding support to a bone and/or making a bone firm, stable, orstationary using a fixation device such as the fixation device 100illustrated in FIG. 1. For example, the term fix or fixing can be theact of holding two or more pieces or fragments of bone in place relativeto each other. In an embodiment, the fixation device 100 can be used inan internal fixation procedure which is an operation in orthopedics thatinvolves the surgical implementation of implants for the purpose ofrepairing a bone 160. During internal fixation, a fixation device, suchas the fixation device 100 illustrated in FIG. 1, is provided to afractured bone to fix the bone 160 and aid in supporting load during thehealing phase. In some embodiments, internal fixation devices may alsoinclude plates, screws, intermedullary (IM) nails or rods, cannulatedscrews, conventional hip screws, and ancillary trauma devices, such aspins, wires, cables, general screws, and staples.

In an embodiment, the fixation device 100 is inserted into an interiorcavity 170 of the bone 160 to fix the bone fracture 150. The interiorcavity 170 may refer to a medullary cavity of a bone or a cancellousbone region of a bone. In some embodiments, the fixation device 100 isan intermedullary (IM) device used to treat bone fractures. The fixationdevice 100 is delivered so that it is contact with the interior surfaceof the bone 160. In some embodiments, the fixation device 100 is evenwith, or flush with, the interior surface of the bone 160. In otherembodiments, the fixation device 100 is delivered adjacent to anexterior surface of the bone 160.

The fixation device 100 may be inserted up to a pre-determined depth inthe interior cavity 170 that is past the bone fracture 150. In someembodiments, the fixation device 100 is inserted into the interiorcavity 170 of the bone 160 such that the distal interface 140 is beyondthe bone fracture 150. In one embodiment, the fixation device 100 isinserted into the interior cavity 170 of the bone 160 and aligned withthe bone 160 so that the bone fracture 150 is positioned at a half-waypoint (i.e., equidistant) between the proximal interface 110 and thedistal interface 140. The position of bone fragments along the axis ofthe fixation device 100 is maintained by the proximal interface 110 andthe distal bone interface 140.

In an embodiment, the proximal interface 110 is a proximal end of thefixation device 100 and may refer to the end of the fixation device thatis closest to the person implanting the fixation device 100. Theproximal interface 110 provides an interface for various tools used toinstall, advance, and retract the fixation device 100 from the interiorcavity 170. The proximal interface 110 can be coupled to a proximal endof the fixation device 100 and coupled to the locking interface 120. Theproximal interface 110 will be described in greater detail below withrespect to FIGS. 2a -2 d.

In an embodiment, the locking interface 120 is configured to convert themain body 130 of the fixation device 100 from a flexible state to arigid state. A flexible state refers to a state in which the fixationdevice 100 is more flexible than in the rigid state. A rigid staterefers to a state in which the fixation device 100 is less flexible thanin the flexible state. The rigid state may refer to a state in which thefixation device 100 has a lower degree of flexion as compared to theflexible state. The degree of flexion for the fixation device in therigid sate may vary depending on the architecture and/or geometry of thebone 160 the fixation device 100 is fixing. In one embodiment,converting from the flexible state to the rigid state may refer tochanging a flexion degree of the fixation device 100. In the rigidstate, the fixation device 100 may still have some degree of flexion;however the fixation device 100 can support the loads as required in thehealing phase of patient treatment.

In an embodiment, the locking interface 120 is positioned between theproximal interface 110 and the main body 130. When the locking interface120 is actuated by a tool via the proximal interface 110, the lockinginterface 120 causes the main body 130 to convert from the flexiblestate to the rigid state. In some embodiments, the locking interface 120is a component of the proximal interface 110. The locking interface 120will be described in greater detail below with respect to FIGS. 3a -3 f.

In an embodiment, the main body 130 is positioned between the lockinginterface 120 and the distal interface 140. The main body 130 has aflexible state and a rigid state. In a flexible state, the components ofthe main body 130 can flex in one or more axes of motion to allow thefixation device to be installed thru arched internal bone passages froma single point. In the rigid state, the components of the main body 130support the loads required by the bone 160 to which the fixation device100 is coupled. After conversion from the flexible state to the rigidstate, the main body 130 maintains the final arched geometry necessaryto maintain the relative position of the fractured bone segments. Themain body 130 will be described in greater detail below with respect toFIGS. 4a -4 d.

In an embodiment, the distal interface 140 is a distal end of thefixation device 100 and may refer to the end of the fixation device 100that is farthest away from the person implanting the fixation device100. The distal interface 140 anchors the fixation device 100 to theinterior cavity 170. The distal interface 140 will be described ingreater detail below with respect to FIGS. 5a -5 b.

Various embodiments of the proximal interface 210 are now shown (FIGS.2a-2c ). For example, FIG. 2a depicts a cut-away view of the proximalinterface 210. In an embodiment, the proximal interface 210 anchors theproximal end of the fixation device to an outer (i.e., exterior) surfaceof the bone. The proximal interface 210 may be an individual componentor a set of components that together form the proximal interface 210. Insome embodiments, the proximal interface 210 includes a set ofcomponents that form an exterior surface 220 that contacts the outersurface of the bone. The exterior surface 220 may include a stepconfiguration to mate to the outer surface of the bone and form a sealaround an access point drilled into the outer surface of the bone. Insome embodiments, the proximal interface 210 may be connected to theouter surface of the bone using a set of pins and bores drilled throughthe bone in the proximal interface 210. In other embodiments, theexterior surface 220 is threaded and engages the outer surface of thebone or an interior surface of the access point.

To engage the outer surface, the proximal interface 210 is rotated usinga driving tool. In an embodiment, the proximal interface 210 includes aninterior surface 230 that includes various configurations to receive andengage a driving tool. For example, FIG. 2b depicts a top view of theproximal interface 210 with a hex pattern to receive the driving tool.In other embodiments, the interior surface 230 of the proximal interface210 may include a star pattern or a threaded pattern or a hexalobepattern to receive the driving tool. The driving tool is inserted intothe proximal interface 210 and rotated until the proximal interface 210is even with or flush with the access point drilled into the outersurface of the bone.

The proximal interface 210 can transfer energy (i.e., torque,compression, tension) from the driving tool to the other components ofthe fixation device (e.g., the locking interface, the main body, thedistal interface). In an embodiment, the proximal interface 210 and thedistal interface transfer load from the bone to the fixation device andvice versa.

In an embodiment, the interior surface 230 of the proximal interface 210includes two portions, a first portion (proximal end) to actuate theproximal interface 210 and a second portion (distal end) to allow accessto the locking interface thru the proximal interface 210. For example,the proximal interface 210 can rotate independent of the lockinginterface, the main body, the distal interface, or the device in thebone in general. In one example, the engagement with and/or movement ofthe locking mechanism/interface does not change the shape, position, orlength of the fixation device. The proximal interface 210 can have adriving torque feature in the first portion to allow the proximalinterface 210 to be advanced into position and engage with the surfaceof the bone without actuating the locking interface. The interiorsurface 230 can be rotated over the fixation device and up and into thebone.

The second portion of the interior surface 230 can include inner threadsto engage with the locking interface or the main body. In an embodiment,the proximal interface 210 allows passage of some portion of the lockingmechanism through its center, such that the locking mechanism, distal tothe proximal interface 210, may be actuated while holding the proximalinterface 210 steady relative to the bone surface. The proximalinterface 210 may include a central bore or access point 240 to providea pathway for a driving tool to engage the locking interface thru theproximal interface 210. FIG. 2c depicts a side view of the proximalinterface 210.

Now referring to FIG. 2d ; FIG. 2d depicts an alternative embodiment tothe proximal interface 210. Proximal interface 215 of FIG. 2d includes aproximal assembly having a proximal threaded exterior surface 222. Theproximal threaded exterior surface 222 can engage with the surface ofthe bone, including the interior surface or the outer surface of thebone to secure the fixation device on one end to the bone. The proximalthreaded exterior surface 222 may include cutting threads. The proximalinterface 215 may include internal threads that engage with a lockinginterface or a main body of a fixation device. The threads on theproximal threaded exterior surface 222 may be of a higher pitch than thethreads on the distal surface, such that rotation of the proximalinterface 215 when engaged with the bone causes compression of thematerial engaged between the threaded proximal exterior surface 222 ofthe proximal interface 215 and threads of the distal interface. In otherembodiments, the threads on the proximal threaded exterior surface 222may be of a lower pitch than threads on a surface of the distalinterface, such that the bone fragments would be forced together as boththreads interact with the bone. In an alternative embodiment,embodiment, the pitches of the threads may not be different.

FIG. 3a depicts a locking interface 320 in accordance with anillustrative embodiment. The locking interface 320 includes a lockingscrew 330, a ram 340, a plurality of fibers 350, and a locking face 360.In an embodiment, the locking screw 330 can move through the lockinginterface 320 to actuate the ram 340. For example, the locking screw 330can be advanced against the ram 340 by a driving tool inserted into theproximal interface. The ram 340 can move each pair of fibers 350radially inside an outer shell 370 in opposing directions. For example,for each fiber pair 350, the ram 340 moves one fiber 350 clockwise andthe other fiber 350 counter-clockwise. The distal end of the ram 340 haspair of faces that can be defined by the position of the fibers 350 inthe unlocked position plus some radial offset, a transition length, andposition of the fibers 350 in the locked position. In an embodiment, theram 340 is advanced until the fibers 350 are in contact with the lockingface 360.

The locking face 360 can have a similar or same contour as the contourof the distal end face of the ram 340, plus some offset equal to apercentage of the fiber diameter. The net space remaining between theram 340 and the locking face 360 is a percentage of the fiber diameter,so that a controlled amount of fiber pinch can be produced in theactuated state. The faces of both the ram 340 and the locking face 360may be of a smooth profile, or stepped profile, as illustrated in FIGS.3b -3 c.

In more detail, FIGS. 3b and 3c depict a step configuration for both thepair of faces 345 of the ram 340 and the locking face 360. FIG. 3b showsthe locking face 360 in a flexible state (unlocked state), where thefibers 350 are spaced a certain distance from each other to allowmovement in one or more axes of motion relative to the other fibers 350.The spacing of the fibers 350 in the flexible state can correspond tothe flexibility or bend radius of the fixation device when it is in theflexible state. FIG. 3c shows the locking face 360 in the rigid state(locked state), where the fibers 350 are clamped together using thefaces 345 of the ram 340 and the locking face 360 to limit or restrictthe motion of the fibers relative to each other. The step configurationadds additional fiber grip in the locked state. The resultinginterference between the components when the locking screw 330 is drivenfully into place creates a clamping force that holds each fiber 350 inits position, without any change in its position relative to the otherfibers 350 in the assembly.

In other embodiments, the locking interface 320 includes a series ofstacked plates. Each plate can have fiber bores (holes) for fibers 350offset in an alternating pattern from a free fiber position and acentral bore (hole) to receive a guide wire or locking pin. In theunlocked position (i.e., flexible state), the center bores in the platesare offset relative to each other and the fiber holes are inlinerelative to each other, allowing the fibers 350 free movement. In thelocked state (i.e., the rigid state), a locking pin can be inserted intothe center bore of the plates extending through all of the plates in theseries of plates and forcing the plates inline relative to thecenter-bore. The fiber bore holes and fibers are offset relative to eachother in the locked state and this creates a gripping action on thefibers 350, holding each fiber 350 in its position, without any changein its position relative to the other fibers 350 in the assembly.

FIGS. 3d and 3e depict a cross sectional locking interface in unlockedand locked states, respectively, in accordance with an illustrativeembodiment. For example, FIGS. 3d and 3e show the ram 340, the lockingface 360, and the fibers 350. FIG. 3d shows the unlocked state, and FIG.3e shows the locked state where the fibers 350 (or cables) are pinchedin order to lock the fibers 350 into position.

In FIG. 3f , an alternative embodiment of a locking interface 325 isshown. The locking interface 325 includes a driving screw (lockingscrew) 335, an interior body 365, an outer body 375, and a plurality offibers 355. In an embodiment, the interior body 365 includes fiber boresto house the plurality of fibers 355 and is externally tapered. Theouter body 375 may be internally tapered. The tapered section on theinternal body 365 is wrapped around each fiber bore such that whenadvanced to a tapered section in the outer body 375, the internal body365 flexes inward, pinching the fibers 355.

In an embodiment, the locking screw 335 has a central bore or iscannulated to allow passage of a guide wire in the locked or unlockedstate. The locking screw 335 can pass fully through the interior body365. The locking screw 335 can have a retention cap on the distal end ofthe locking screw 335 to contact and engage the interior body 365. Forexample, rotation of the locking screw 335 in the clockwise directioncan advance the interior body 365 to a locked state. Rotation of thelocking screw 335 in the counterclockwise direction can retract orrelieve the pressure on the interior body 365 causing it to retract tothe unlocked state.

FIG. 4a depicts a main body 430 in accordance with an illustrativeembodiment. The main body 440 includes a series of beads 440 coupledtogether to form the main body 440. In an embodiment, the beads 440include a pair of lobes 450, a pair of sockets 460, and a central pivotpoint 470. The body 430 may change shape from straight, where norelative angulation is present, to the approximation of a curvature asbeads tilt upon the central pivot point 470. The main body 430 has aflexible state and a rigid state, independent of main body shape,controlled by the state of the locking mechanism in the proximal end210.

To connect each bead 440 to a subsequent or preceding bead 440 in theseries of beads, the pair of lobes 450 connects into a pair of socketsof a next bead 440. The beads 440 can be limited in axial movement bythe configuration and dimensions of the lobes 450 and the sockets 460.Each lobe 450 in the pair of lobes can be located at opposing ends ofbead 440. For example, the lobes 450 in a pair of lobes 450 may beequidistant from each other. In other embodiments, the lobes 450 may beoffset a pre-determined degree relative to one another. The lobes 450may extend perpendicular from a first surface of the bead to connect tothe sockets 460.

In an embodiment, the sockets 460 are formed into a second surface of abead 440. The second surface may be the opposite surface from the firstsurface of the bead 440. Each socket 460 in the pair of sockets can belocated at opposing ends of the bead. For example, the sockets 460 in apair of sockets 460 may be equidistant from each other. In otherembodiments, the sockets 460 may be offset a pre-determined degreerelative to one another.

In an embodiment, the central pivot point 470 is located at a centralpoint on a second surface of the bead, for example the same surface asthe sockets 460. The central pivot point 470 adjoins or contacts a nextsequential bead 440 in the series of beads. The central pivot point 470may include a central bore 480 formed through it.

FIGS. 4b-4d illustrate a bead 440 at different angles to show theconfiguration of the pair of lobes 450, the pair of sockets 460, and thecentral pivot point 470. FIG. 4b and FIG. 4c depict different side viewsof the bead 440. The pair of lobes 450 extends perpendicular from aplane of the first surface of the bead 440. The sockets 460 are formedinto an opposite side, the second side of the bead. The pair of lobes450 and the pair of sockets may be positioned along an edge or outercircumference of the bead 440.

FIG. 4d depicts a top view of the bead 440. As illustrated in FIG. 4d ,each bead 440 includes a central bore 480 or a hollow core and fiberbores 490. The central bore 480 can receive a guide wire which can beused to direct a fixation device through an interior cavity of a bone.In one embodiment, each bead 440 has three fiber bores 490 to housefibers. In other embodiments, the number of fibers bores 490 may rangefrom at least one to a number corresponding to the number of fibers tobe used in the fixation device.

The beads 440 separate and support a series of tensile fibers that arehoused within the fiber bores 490 of the beads 440. The main body 440has two states that it can convert between, a flexible state and a rigidstate. In the flexible state, the fibers are axially fixed to the distalinterface only, with the fibers free to translate through theirrespective bores in each bead 440.

The surfaces of the beads can limit the bead to bead angulation to apre-determined maximum angle, resulting in a device minimum bend radius.For example, the face of a bead 440 that surrounds an edge of thecentral pivot point 470 can limit the bead to bead angulation to apre-determined maximum angle, resulting in a device minimum bend radius.In an embodiment, the beads have a fiber bores 490 spaced around thecentral bore 480 that maintain tensile fibers at a distance from thecenter of the bead 440, as well as in a specific radial position (i.e.at 0°, 60°,120°,180°, 240°, 300°, 360°). The tensile fibers members mayterminate within the main body 430, or in members attached to either endof the main body 430, such as a proximal interface, a locking interface,or a distal interface. When the bead to bead angulation is limited, anadditional advantage for recovery of a fracture is that the beads cantransfer tensile load in addition to and/or instead of the cables ortensile fibers in the main body.

For example, in a rigid state, the fibers are fixed in position at theproximal interface and the translation of the fibers becomes limited. Insome embodiments, the three fibers must be in place in the main body 430to provide bead fixation about all planes of movement. In otherembodiments, additional fibers may be added to provide additionalstrength, as well as a more uniform flexural stiffness in any bendingaxis with respect to the fibers pattern orientation. The fiber bores 490in each bead 440 can form a lateral support for each fiber, keeping thefibers away from the neutral bending axis, such that when the rigidassembly experiences a transverse load, the transverse load creates apurely tensile load in any fiber on the opposite side of the bendingaxis from the transverse load. In an embodiment, the assembly of thefibers inside the fiber bores 490 of each bead provides a torquetransmission capability when beads 440 are in close proximity, equal tothe shear strength of that of the sum of at least two fibers, and atmost the total number of fibers in the assembly.

Now referring to FIG. 5a , a distal interface 540 in accordance with anillustrative embodiment is shown. In an embodiment, the distal interface540 anchors the distal end of a fixation device to an interior surfaceof a bone. For example, the distal interface 540 can be mated (engaged)into an interior cavity of the bone to secure the distal end of thefixation device to the bone. The distal interface 540 can transfer loadfrom the bone to the fixation device and vice versa when attached to thebone.

The distal interface 540 may be an individual component or a set ofcomponents that together form an exterior surface that contacts theinterior bone surface at the distal end of the fixation device. In anembodiment, the distal interface 540 includes a threaded exteriorsurface 550. The threaded surface 550 can engage and mate with theinterior surface of the bone to connect the distal end of the fixationdevice top the bone. The threads of the threaded surface 550 can beconfigured in a geometry that allows retention of the distal interface540 to the interior region of the bone. In an embodiment, the threadedexterior surface 550 includes different types of threads, includingthreads of different sizes. For example, in one embodiment, the threadedexterior surface 550 includes cutting threads that remove and directtissues in front of threads at a major diameter of the body of thedistal interface, reducing the torque required to drive the fixationdevice into the interior region of the bone.

In an embodiment, the distal interface 540 may be hollow or include acentral bore 560 to receive a guide wire and/or a central tensioningmember. The interior surface of the distal interface may also be thedistal termination point for tensile fibers extending though thefixation device. In an embodiment, the fibers of the fixation device maybe in a fixed position in the distal interface 540 during both theflexible state and the rigid state. The root face of the head of thedistal interface 540 may have a tapered profile that can rotate throughan arched lumen profile as illustrated in FIG. 5 b.

Now referring to FIG. 6, a flow diagram of a method for delivering afixation device to a bone of a patient is shown. As a brief overview,the method includes installing the fixation device in a flexible stateinto an interior cavity of the bone via an access point in the bone(step 610). The fixation device includes a flexible state and a rigidstate. The method further includes rotating a proximal end of thefixation device using a driving tool to secure a distal end of thefixation device into the interior cavity of the bone (step 620). Themethod further includes actuating a locking interface of the fixationdevice via the proximal interface to convert the fixation device from aflexible state to a rigid state (step 630).

To deliver the fixation device to the bone of the patient, an access orpathway to the bone can be established through soft tissue surroundingthe bone. In an embodiment, access to the bone is provided by a cannulaplaced through the soft tissue. Once the surface of the bone is reached,a hole or access point is made in the hard outer bone (i.e., corticalbone). The access point provides access to the interior bone surface orthe cancellous bone region.

Next, a guide is placed though the cannula and into the interior cavityof the bone. In an embodiment, the guide is a low stiffness, bent tipsteerable guide. The guide can be driven into the interior cavity of thebone under fluoroscopic observation. In an embodiment, the guideincludes a sharp tip that is advanced and oriented toward the interiorof the bone curvature, such that the tip does not dig into the exteriorcortical wall. The steerable guide can follow the interior geometry ofthe bone to a desired or pre-determined depth past a fracture in thebone. The desired depth may be a point to allow a middle portion of afixation device to be aligned with the fracture such that the distal endand proximal end of the fixation device receive and transfer similar orthe same amounts of load between the fixation device and the bone onceattached. In other embodiments, the desired depth may vary depending onthe shape or geometry of the bone and where the fracture is in the bone.

When the guide has reached the desired depth, the guide may be replacedwith a blunt tip guide wire. A flexible reamer can then be fed over theguide wire and through the interior cavity of the bone. The reamerincreases the diameter of a bore through the interior cavity in the bonealong the same path as the guide wire. The diameter may be increased toa point that allows the fixation device to be delivered and installedinside the bone.

Once the diameter of the bore has been increased to the appropriatesize, the reamer is removed and exchanged with the fixation device. Thefixation device can be inserted a flexible state into the interiorcavity of the bone via the access point in the bone (step 610). Thefixation device includes a flexible state and a rigid state. Thefixation device can be delivered up to the exterior surface of the boneusing the cannula.

The method further includes advancing the fixation device to apre-determined point past a fracture in the bone. As stated above, thedesired depth may be a point to allow a middle portion of a fixationdevice to be aligned with the fracture such that the distal end andproximal end of the fixation device receive and transfer similar or thesame amounts of load between the fixation device and the bone onceattached. In other embodiments, the desired depth may vary depending onthe shape or geometry of the bone and where the fracture is in the bone.

The method further includes rotating a proximal end of the fixationdevice using a driving tool to secure a distal end of the fixationdevice into the interior cavity of the bone (step 620). When thefixation device reaches the exterior surface of the bone to be fixed,the fixation device can be rotated using a driving tool that interfaceswith a proximal interface of the fixation device. The rotation of theproximal interface transmits torque through a locking interface and mainbody of the fixation device to the distal interface of the fixationdevice.

The distal interface may include a threaded exterior surface that pullsthe distal interface and the fixation device into the bore of theinterior cavity of the bone. The proximal interface is rotated until theproximal interface is adjacent to the exterior surface of the bone orflush with the access point created in the exterior surface of the bone.When the fixation device reaches the desired depth, the guide wire canbe removed.

The method further includes actuating a locking interface of thefixation device via the proximal interface to convert the fixationdevice from a flexible state to a rigid state (step 630). In anembodiment, a driving tool is inserted into the proximal interface andengages an inner thread of the interior surface of the proximalinterface. The inner thread provides a path to the locking interfacethrough the proximal interface such that when the locking interface isrotated, the fixation device does not move relative to the bone, and canbe converted from the flexible state to the rigid state.

In an embodiment, a locking screw of the locking interface is advancedthrough the locking interface to contact with a ram or interior body. Inone embodiment, the ram rotates fibers in opposing directions causingthe fibers to pinch against a locking face of the locking interfaceuntil they are clamped or restricted from moving. The restriction of thefibers restricts the movement and flexion of a main body of the fixationdevice. The main body includes a series of beads that are connectedtogether and house a portion of the fibers. When the fibers arerestricted in movement, the series of beads and fibers combine to form arigid member. The degree of movement of the fibers may correspond to thedegree of movement of the series of beads. For example, in the rigidstate, the series of beads making up the main body are aligned relativeto one another and restrict the motion of the fiber in the main body. Inthe rigid state, the movement of the fibers is restricted at theproximal end of the fixation device and the distal end of the device.Alternatively, in the flexible state, the movement of the fibersrelative to one another is only restricted at the distal end of thefixation device.

In other embodiments, the interior body of the locking interface isadvanced to a tapered section of the locking interface and appliespressure on the tensile fibers housed in the main body. The pressurepinches the fibers limiting and restricting their ability to move. Therestriction from either the ram or the interior body movement causes thefibers to be offset relative to another fiber in the main body of thefixation device. The restriction causes the fibers to be offset relativeto another fiber in the main body of the fixation device. In anembodiment, a series of beads making up the main body are alignedrelative to one another and restricts the motion of the fibers in themain body. In the rigid state, the movement of the fibers is restrictedat the proximal end of the fixation device and the distal end of thedevice. In the flexible state, the movement of the fibers relative toone another is only restricted at the distal end of the fixation device.The final rigid state of the fixation device will depend on thecurvature or geometry of the bone to which the fixation device isattached. The fixation device can be tightened and loosened toaccommodate the shape of the bone. In some embodiments, fibers can beadded or removed from the fixation device prior to installation toincrease or decrease the bend radius of the fixation device and strengthof the device.

Now referring to FIG. 7a , a locking interface 710 is shown in theunlocked position. A collet housing 720 houses a collet 730 and a colletlock 740. The collet 730 has an ID in the open state of such size topermit all device cable and a guide wire to pass through. The proximalend of the collet 731, in the closed state reduces to a size sufficientto clamp 3 or more cables, without a guide wire in place. The colletlock 740 extends partially out of the collet housing 720 in the unlockedstate, exposing threads 741. The exposed threads 740 of the collet lock740 may be engaged with an insertion tool to handle the fixation device.The collet lock distal taper 742 interfaces with the collet arms 731, tosqueeze teeth radially inward until such point that the cables of thedevice are gripped by the collet teeth 732. Collet Cable Reliefs 743permit the cables to pass into the center of the collet 730, and preventthe collet from rotation within the collet housing 720. FIG. 7b depictsa collet 730 and collet lock 740 in accordance with an illustrativeembodiment. The collet 730 and collet lock 740 of FIG. 7b may be similarto and used similar to the similarly numbered components of FIG. 7a .For example, the collet 730 includes the collet arms 731 and the colletlock 740 includes the threads 741.

In some embodiments, if the fixation device needs to removed, an accesspoint must be made again through the soft tissue using the methods asdescribed above. Once access to the fixation device is established, thedevice can be converted from the rigid state to the flexible state. Thelocking interface can be disengaged to allow flexion in the main body ofthe fixation device. In the flexible state, the device can be rotatedout of the interior cavity of the bone using a driving tool interfacedwith the proximal interface of the fixation device. The rotation cantransmit torque through the main body of the device, up to the distalinterface of the fixation device. In an embodiment, the torsionalresponse of the main body sections will result in a section by sectiondisengagement with any bone ingrowth, with the most proximal sectionbreaking free of ingrowth first, then the second, then the 3 rd, etc.When the entire main body of the fixation device has broken free of boneingrowth, torque will be transmitted into the distal interface.

In an embodiment, the locking interface is rotated counter clockwise toretract the fixation device from the interior cavity of the bone. Whendriven counter clockwise, the threads on the head and exterior surfaceof the distal interface can push the fixation device out the bore of thebone until the distal end of the device reaches the exterior surface ofthe bone.

In other embodiments, to remove the fixation device a centering drillguide is applied over the proximal end of the fixation device. A thinwalled flexible hole-saw matched with the outer diameter of the devicemay be used to cut away the bone around the device. The hole-saw isremoved and the locking interface is disengaged to allow flexion in themain body of the fixation device. In the flexible state, the fixationdevice can be pulled from the bore of the bone.

In an embodiment, the four sections of the fixation device, the proximalinterface 110, the locking interface 120, the main body 130, and thedistal interface 140, are modular to a degree, such that the alternateembodiments described for each device section may be readilyinterchanged. All sections can be manufactured using standard machining,electrical discharge machining (EDM), and/or forging methods, forexample, from 316LVM Stainless steel material. Other implantablematerials may also be feasible for use, including but not limited to TiGrade 23 6AI-4V extra low interstitial (ELI), and polyether ether ketone(PEEK). The use of the term “fiber” is inclusive of a multitude of crosssections including (but not limited to) round, rectangular, square, andbundles of any of the former.

One or more flow diagrams may have been used herein. The use of flowdiagrams is not meant to be limiting with respect to the order ofoperations performed. The herein described subject matter sometimesillustrates different components contained within, or connected with,different other components. It is to be understood that such depictedarchitectures are merely illustrative, and that in fact many otherarchitectures can be implemented which achieve the same functionality.In a conceptual sense, any arrangement of components to achieve the samefunctionality is effectively “associated” such that the desiredfunctionality is achieved. Hence, any two components herein combined toachieve a particular functionality can be seen as “associated with” eachother such that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (for example, bodiesof the appended claims) are generally intended as “open” terms (forexample, the term “including” should be interpreted as “including butnot limited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood by those withinthe art that if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (for example, “a” and/or “an” should typically be interpreted tomean “at least one” or “one or more”); the same holds true for the useof definite articles used to introduce claim recitations. In addition,even if a specific number of an introduced claim recitation isexplicitly recited, those skilled in the art will recognize that suchrecitation should typically be interpreted to mean at least the recitednumber (for example, the bare recitation of “two recitations,” withoutother modifiers, typically means at least two recitations, or two ormore recitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (for example, “a system having at leastone of A, B, and C” would include but not be limited to systems thathave A alone, B alone, C alone, A and B together, A and C together, Band C together, and/or A, B, and C together, etc.). In those instanceswhere a convention analogous to “at least one of A, B, or C, etc.” isused, in general such a construction is intended in the sense one havingskill in the art would understand the convention (for example, “a systemhaving at least one of A, B, or C” would include but not be limited tosystems that have A alone, B alone, C alone, A and B together, A and Ctogether, B and C together, and/or A, B, and C together, etc.). It willbe further understood by those within the art that virtually anydisjunctive word and/or phrase presenting two or more alternative terms,whether in the description, claims, or drawings, should be understood tocontemplate the possibilities of including one of the terms, either ofthe terms, or both terms. For example, the phrase “A or B” will beunderstood to include the possibilities of “A” or “B” or “A and B.”

The foregoing description of illustrative embodiments has been presentedfor purposes of illustration and of description. It is not intended tobe exhaustive or limiting with respect to the precise form disclosed,and modifications and variations are possible in light of the aboveteachings or may be acquired from practice of the disclosed embodiments.It is intended that the scope of the invention be defined by the claimsappended hereto and their equivalents.

1. An apparatus for intermedullary bone fracture fixation, the apparatus comprising: a main body of a fixation device having a flexible state and a rigid state; a proximal interface coupled to a proximal end of the main body to anchor the fixation device to an exterior surface of the bone; a distal interface coupled to a distal end of the main body to anchor the fixation device to an interior cavity of the bone; and a locking interface configured to convert the main body from the flexible state to the rigid state, wherein the locking interface is coupled to the proximal interface.
 2. The apparatus of claim 1, wherein the main body comprises a series of beads, and wherein each bead in the series of beads comprises a central bore and three or more fiber bores positioned around the central bore.
 3. (canceled)
 4. (canceled)
 5. (canceled)
 6. (canceled)
 7. The apparatus of claim 1, wherein each bead comprises: a pair of lobes positioned at opposing ends of the respective bead and extending perpendicular from a first surface of the respective bead; a pair of sockets formed into a second surface of the respective bead and positioned at opposing ends of the respective bead, wherein the pair of sockets is configured to receive the pair of lobes of a preceding bead in the series of beads to form the series of beads; and a central pivot point on the first surface of the respective bead that contacts a subsequent bead in the series of beads.
 8. (canceled)
 9. (canceled)
 10. (canceled)
 11. The apparatus of claim 1, wherein the proximal interface comprises: an exterior surface that connects to the exterior bone surface; and an interior surface configured to receive a driving tool.
 12. (canceled)
 13. The apparatus of claim 11, wherein the internal surface of the proximal interface comprises an access point to connect the locking interface to a driving tool when the driving tool is inserted into the proximal interface.
 14. (canceled)
 15. (canceled)
 16. The apparatus of claim 1, wherein the locking interface comprises: a locking screw; a threaded portion; an outer shell housing a pair of fibers; a locking ram; and a locking face.
 17. The apparatus of claim 16, wherein the locking screw is configured to receive a driving tool via an access point in the proximal interface.
 18. The apparatus of claim 16, wherein the locking screw is configured to advance the locking ram and the locking ram is configured to rotate each fiber of the pair of fibers housed in the outer shell in opposing directions.
 19. The apparatus of claim 18, wherein a distal end of the locking ram comprises a pair of faces configured to rotate the pair of fibers.
 20. The apparatus of claim 19, wherein a contour of the locking face is the same as a contour of the pair of faces of the distal end of the locking ram.
 21. The apparatus of claim 19, wherein the pair of faces of the distal end of the locking ram clamp the pair of fibers to the locking face in the rigid state.
 22. The apparatus of claim 1, wherein the locking interface comprises a series of plates, wherein each plate in the series of plates comprises a central bore and a pair of fiber bores to house a pair of fibers.
 23. The apparatus of claim 22, wherein the central bore of each plate is offset relative to the central bore of a subsequent plate in the series of plates when the fixation device is in the flexible state, and wherein the pair of fiber bores of each plate is inline relative to the pair of fiber bores of a subsequent plate when the fixation device is in the flexible state.
 24. The apparatus of claim 22, wherein the series of stacked plates comprises a locking pin inserted through the central bore of each plate when the fixation device is in the rigid state, wherein the central bore of each plate is inline relative to the central bore of a subsequent plate in the series of plates when the fixation device is in the rigid state, and wherein the pair of fiber bores of each plate is offset relative to the pair of fiber bores of a subsequent plate when the fixation device is in the rigid state.
 25. The apparatus of claim 1, wherein the locking interface comprises: a locking screw; an interior body comprising an externally tapered shape; and an outer body comprises an internally tapered shape.
 26. The apparatus of claim 25, wherein the interior body comprises a central bore to receive a guide wire and a plurality of fiber bores to house a plurality of fibers.
 27. The apparatus of claim 25, wherein a distal end of the locking screw comprises a cap configured to contact the interior body to advance the interior body to a tapered portion of the outer body when the locking screw is rotated clockwise.
 28. The apparatus of claim 25, wherein locking screw is configured to retract the interior body when the locking screw is rotated counter clockwise.
 29. The apparatus of claim 1, wherein the distal interface comprises a threaded outer surface to anchor the fixation device to the interior cavity of the bone when the fixation device is installed in the interior cavity of the bone.
 30. (canceled)
 31. A method for delivering a fixation device to a bone of a patient, the method comprising: delivering the fixation device in a flexible state into an interior cavity of the bone via an access point in the bone, wherein the bone comprises a fracture; rotating a proximal end of the fixation device using a driving tool to secure a distal end of the fixation device into the interior cavity of the bone, wherein the proximal end is flush with the access point of the bone; and actuating a locking interface of the fixation device via the proximal interface to convert the fixation device from the flexible state to a rigid state.
 32. (canceled)
 33. (canceled)
 34. (canceled)
 35. (canceled)
 36. The method of claim 31, wherein the fixation device comprises a main body comprising a series or beads, a proximal interface coupled to a proximal end of the main body; a distal interface coupled to a distal end of the main body; and a locking interface configured to convert the fixation device from a flexible state to a rigid state, wherein the locking interface is coupled to the proximal interface.
 37. The method of claim 36, wherein each bead in the series of beads comprises a central bore and three or more fiber bores positioned around the central bore.
 38. The method of claim 37, wherein the main body further comprises three or more fibers that run a length of the main body and wherein each of the three or more fiber bores houses one of the three or more fibers.
 39. (canceled)
 40. (canceled)
 41. The method of claim 36, wherein each bead comprises: a pair of lobes positioned at opposing ends of the respective bead and extending perpendicular from a first surface of the respective bead; a pair of sockets formed into a second surface of the respective bead and positioned at opposing ends of the respective bead, wherein the pair of sockets are configured to receive the pair of lobes of a preceding bead in the series of beads to form the series of beads; and a central pivot point on the first surface of the respective bead that contacts to a subsequent bead in the series of beads.
 42. (canceled)
 43. (canceled)
 44. (canceled)
 45. The method of claim 31, further comprising securing the proximal interface to an exterior surface of the bone, wherein the proximal interface is flush with the access point of the bone, and rotating the proximal interface to engage a threaded exterior surface of the proximal interface with the exterior surface of the bone.
 46. (canceled)
 47. (canceled)
 48. The method of claim 31, wherein an internal surface of the proximal interface comprises an access point to connect the locking interface to the driving tool when the driving tool is inserted into the proximal interface.
 49. (canceled)
 50. (canceled)
 51. The method of claim 36, further comprising receiving, by a locking screw of the locking interface, a driving tool via an access point in the proximal interface.
 52. The method of claim 51, further comprising rotating the locking screw to actuate a locking ram of the locking interface.
 53. The method of claim 52, further comprising rotating the locking ram to rotate each fiber of a pair of fibers housed in the locking interface, wherein the pair of fibers are rotated from the flexible state to the rigid state.
 54. The method of claim 53, wherein a distal end of the locking ram comprises a pair of faces configured to rotate the pair of fibers.
 55. The method of claim 54, further comprising clamping, by the pair of faces of the locking interface, the pair of fibers to a locking face of the locking interface in the rigid state.
 56. The method of claim 36, wherein the locking interface comprises a series of plates, wherein each plate in the series of plates comprises a central bore and a pair of fiber bores to house a pair of fibers.
 57. (canceled)
 58. (canceled)
 59. The method of claim 36, further comprising actuating an interior body of the locking interface with a distal end of a locking screw of the locking interface.
 60. (canceled)
 61. (canceled)
 62. (canceled) 